(1) Field of the Invention
The present invention relates to a method for the surface treatment of a powdery and granular material stored in the open air which makes use of an aqueous emulsion type surface treating agent, and according to this method, a film is formed on the surface of the powdery and granular material stored in the open air to prevent the dusting, deterioration, outflow and destruction of the particle material and to inhibit the increase of water content owing to rainfall.
(2) Description of the Prior Art
Powdery and granular materials such as coals, ores, earths and sands are often stored in a large amount in the open air. Therefore, such field-stored materials are apt to dusting, outflow and destruction and tend to cause environmetal pollution. Furthermore, in such a case, there are many problems such as a quality deterioration due to the weathering and heat generation of the powdery and granular materials and an increase of water content therein resulting from rainfall, which requires energy to restore the dry condition. Accordingly, in order to overcome such problems regarding the open-air storage of the powdery and granular materials, researches have been conducted on a variety of methods for the surface treatment of the stored materials (for example, "Sentan", Vol. 7, 1957, p. 300 and Japanese Patent Provisional Publication No. 109557/1983). However, for reasons of economy and inadaptability to a use of the powdery and granular material, those materials which can be actually utilized as surface treating agents are limited to a fairly narrow range.
Taking the role of the surface treating agent into consideration, a raw material used as the agent is required to have adhesive properties and hydrophobic nature and, most of all, to be inexpensive. The raw materials which can satisfy such requirements include petroleum fractions such as high-viscosity oil and asphalt. However, the strength of the film formed from the high-viscosity oil is not sufficient for the surface treatment, and on the other hand, the asphalt cannot display a good waterproof performance when formed into a thin coating.
The inventor of the present case has intensively made investigations with the aims of solving the above-mentioned problems regarding the surface treatment of the powdery and granular materials stored in the open air, and of overcoming the drawbacks of the known surface treating agents, and finally the present invention has been completed.